Co-extrusion 3D printing improves solar cells and battery

Mar.14, 2013 | By Anne van der Meij

A solar cell converts light energy directly into electrical energy. The more light is exposed to the cell, the more light is absorbed and the more electrical energy is generated. Even for these complex chemical reactions 3D printing technology is a promising method.

Solar cells have gridlines on their front surfaces to conduct the newly generated energy. These gridlines lie on top of the photovoltaic (light absorbing) material that converts light into electricity. Narrower and taller front gridlines can increase the solar cell’s yield because less of the solar cell's surface is covered. 3D printing technology opens the opportunity to help make solar panels more efficient.

(PARC's co-extrusion printing technique)

PARC (Palo Alto Research Center) is a Xerox company using Xerox technology. They developed an innovative 3D printing technique called co-extrusion (CoEx) which makes it possible to produce narrower and taller gridlines. During CoEx printing dissimilar materials can be deposited side by side at high speed. This technique can deposit an interdigitated structure as small as 5μm, 10 times smaller than the diameter of a human hair. By changing the print head geometry, the relative thickness, width, and length of the deposited structure can easily be modified. In other words CoEx allows the materials to shape each other, creating micron-scale structures smaller than conventional techniques. The technique can handle a lot of different materials including metals, ceramics, and polymers. This system is already in production with a solar cell maker.

A solar cell being printed with PARC's co-extrusion technology.

A solar cell shortly after being printed with PARC's co-extrusion technology.

But PARC hasn't stopped there. PARC researchers have also been using this new manufacturing method to increase the energy density of batteries. Using their co-extrusion printing technology researchers are able to make small channels in the cathode to allow the lithium ions to penetrate deeper.

"By doing that you can make the electrode thicker and as you make it thicker you basically make the energy density for the whole battery higher," Scott Elrod, PARC lab director said to pcworld. "So instead of going a hundred miles on an electric vehicle battery you can maybe go a hundred and twenty miles. We think that the improvement is on the order of 20 percent."

A prototype lithium battery using co-extrusion technology. It was shown during a demonstration at PARC.

Co-extrusion offers a way to economically manufacture structural and hybrid material designs, and can be easily adapted to a wide range of applications including solar cells and batteries. PARC hopes to apply this novel co-extrusion printing technique to make electric car and power tools first.